1. Field of the Invention
The present invention relates to switches and, more specifically, to vehicle steering column mounted switches for controlling vehicle operating circuits and components.
2. State of the Art
The evolution of steering column switches in motor vehicles has been toward greater integration of functions in a single switch lever. Previously, a plurality of individual switches, each controlling a single vehicle function, i.e., turnsignals, windshield wipers, headlights, etc., were mounted on the vehicle dashboard. Current steering column switch levers are designed to control a variety of functions for vehicle operating circuits or devices, such as turnsignals and hazard lights, high beam and low beam headlights with optional flash-to-pass, parking lights, fog lights, windshield wiper and wash functions, including multi-speed wipers with or without intermittent delay.
Typically, a steering column stalk switch includes a single lever or stalk pivotally mounted on one side of a housing attached to the vehicle steering column in an easily accessible position for access by the driver of the vehicle. The lever is gimballed at one end in housing so as to move in one and, typically, two mutually separate planes. Further, the lever may be provided with a rotatable end cap, and/or a slidable member movable along the longitudinal axis of the lever to control additional vehicle operating circuits. An intermediate member on the lever may also be rotatable to control another vehicle circuit or device. Actuators are mounted in the housing and, in response to movement of the lever in different directions or planes, rotation of the end cap, or movement of the slidable member, or rotation of the intermediate member on the lever, move a switching member carrying contacts between various switching positions to effect the switching of electrical connections for a particular vehicle operating circuit.
In some vehicles, particularly vehicles manufactured in Europe and/or Japan, two steering column stalk switches are provided, one mounted on the left side of the steering column and one on the right side of the steering column. The various vehicle operating circuits or devices described above are split between the two stalk switches, with the left stalk switch typically controlling vehicle headlight, parking light, fog light, flash-to-pass operation as well as turnsignal operations. The right mounted stalk lever typically controls windshield wiper, mist and wash devices.
However, regardless of whether one or two stalk switches are employed in a vehicle, vehicle design constraints require that the stalk switch lever and the housing assembly be as small as possible while at the same time providing easy access to and movement of the various switches on the stalk switch(es).
It is common in stalk switch design to have a rotatable actuator, such as a rotatable end cap mounted on an outer end of a stalk switch lever to rotate a drive gear mounted within the stalk switch housing. The drive gear engages a mating gear which carries or is otherwise coupled to an electrical contactor carrying one or more contacts which are disposed for selective engagement with conductive elements or traces on a substrate or printed circuit board mounted within the housing to open and close electrical circuits upon movement of the contactor due to rotation of the end cap.
However, due to the multiple functions normally combined into a single stalk switch lever, the gear pair must be multi-axially oriented with the drive gear rotatable about one rotational axis during one vehicle device operation, such as a windshield wipe cycle. The same gear must also be movable or pivotal about another rotational axis when the lever is pivoted for activating a windshield wash operation and, further, must be movable about yet another rotatational axis upon pivotal movement of the lever about a different axis for a windshield wiper mist operation. This multi-axis design requires tooth profiles that are complex to design and manufacture.
Further, accurate timing during movement of the lever and the internal components about the multiple axis or rotation directions must be precise for a positive tactile feel to the driver and to ensure that the components move the precise amount during each pivotal or rotational movement imparted by the lever or end cap.
It is common in gear pair design to provide backlash which is defined as the amount by which the tooth space of one gear exceeds the tooth thickness of a mating gear at the pitch circle of the gears. That is, the space between two teeth on one gear is larger than the width of each tooth on the mating gear.
This results in looseness in the mating gears which can lead to timing inaccuracies as well as a sloppy tactile feel to the use when operating the stalk switch lever in rotation.
Thus, it would be desirable to provide a vehicle steering column stalk switch having rotative elements operated by mating gears which has improved accuracy and a positive tactile feel to a user during rotation. It would also be desirable to provide a drive gear pair for a vehicle steering column stalk switch lever which has improved accuracy when employed in a multi-axially oriented gear pair.
The present invention is a drive gear pair for a vehicle steering column stalk switch lever which includes a vehicle steering column stalk switch including a housing mountable on a vehicle steering column, a lever movably mounted on the housing, an actuator carried on the lever and rotatable with respect to the lever, a first gear having first gear teeth and coupled to the actuator for rotation with rotation of the actuator, a second gear movably mounted in the housing and having second gear teeth. The first and second gear teeth of the first and second gears, respectively, are engaged with zero backlash. Conductive elements are carried on one of the second gear and the housing. A contact is carried on the other of the second gear and the housing wherein rotation of the actuator causes rotation of the first gear and movement of the second gear to selectively engage the contact with selective conductive elements to open and close electrical circuits therebetween.
In one aspect of the invention, means are provided for biasing the first and second gears into engagement. According to a preferred aspect, the biasing means comprises at least one contact formed as a leaf contact resiliently cantilevered from the conductive elements in the housing. The leaf contact biasingly engages the second gear to bias the second gear into compliant engagement with the first gear.
Counter to conventional gear pair design, the present drive gear pair utilizes mating gear teeth which mesh with zero backlash and zero interference. This enables a more accurate timing to be devised for a vehicle steering column stalk switch apparatus during movement of the rotatable portion of the lever.
The use of zero backlash also enables the multifunction stalk switch lever to provide a more positive tactile feel to a user when rotating the rotatable portion of the lever through various defined detent positions. The use of zero backlash also enables the multifunction switch lever apparatus of the present invention to be constructed with a more simplified assembly method.